Process for imparting color to molded engineering plastics

ABSTRACT

The present invention is directed to processes for colorization of molded articles made from engineering plastics. In particular, the processes are used to colorize ice skate blade holders and goalie skate cowlings.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Non-Provisional of U.S. Provisional Patent Application No. 60/864,371, entitled PROCESS FOR IMPARTING COLOR TO MOLDED ENGINEERING PLASTICS filed Nov. 3, 2006, the entire text of which is hereby incorporated herein by reference in its entirety.

BACKGROUND

This invention is generally directed to a process for imparting color to molded materials. In particular, the invention is directed to a process for imparting color to molded plastic pieces of various sports equipment. In one preferred embodiment, the invention is directed to imparting color to ice skate blade holders and goalie skate cowlings while retaining the other characteristics of the ice skate blade holder or goalie skate cowling, such as logos, model names, etc.

Generally, there are three major components to an ice hockey skate-the boot, the blade and the holder. Traditionally, the boot is constructed of an intricate system of materials including leather, synthetics, fabrics, and plastic inserts. The boot's purpose is to enclose the foot and ankle, providing support and protection. The blade is composed of carbon steel or stainless steel and its purpose is to interface with the ice, allowing the skater to turn, stop, and accelerate. The ice skate holder is a device that permits the attachment of the steel blade to the bottom of the boot. The ice skate holder, normally constructed from molded plastic or polycarbonate resin thermoplastic (Lexan®), is affixed to the bottom of the boot with rivets or bolts and employs various systems of bolts or screws to secure the blade. Goalie cowlings, in addition to providing a structure to which to affix the steel blade, cover the lower portion of the goalie boot, delivering additional protection against the impacts of shots.

Generally, ice skate blade holders and goalie cowlings have been made of white plastic with decorations (logos, model names, etc.) applied in the form of paint or decals. In limited situations, holders have been molded of grey or black plastic. Nike Bauer in 2005 introduced a clear (translucent) Lexan® holder. Many hockey players may prefer wider options with respect to the appearance of the ice skate blade holders or goalie skates that they use. For example, ice skate blade holders and goalie cowlings having a wide array of colors and even colored designs (e.g., player names, numbers, etc.) that would coordinate with a team's colors can be desirable. Most hockey players will choose a holder color or cowling color based on primary, secondary or tertiary colors of the team uniform. The alternative driver of color selection is the presence of the color in another piece of equipment, especially the boot of the skate.

While non-white color variations of the skate holders and goalie cowlings have been produced by colorizing the raw plastic material before molding the skate blade holder or the cowling, a need still exists for a process for imparting color to molded skate blade holders and other molded plastic pieces of sporting equipment.

SUMMARY

Among the various aspects of the invention is a process for colorizing sporting equipment comprising substantially rigid molded portions. These substantially rigid molded portions can be, for example, skate blade holders, goalie skate cowlings, lacrosse racquet heads, and hockey and lacrosse helmets.

Another aspect of the invention is a process for imparting color to a molded article comprising submersing at least a portion of the molded article in a dye bath comprising an aqueous solvent and a dye wherein the molded article is comprised of an engineering plastic.

Other objects and features will be in part apparent and in part pointed out hereinafter.

DETAILED DESCRIPTION

The present invention is directed to processes for imparting color to substantially rigid moldable, colorizable materials, particularly engineering plastics after they are molded into the shape of their product. Generally, the processes for imparting color are used for white or translucent engineering plastics. Typically, this process for imparting color also allows for retention of the logos, model numbers, etc. that the molded material contained before the process imparted color.

Generally, the process for imparting color comprises immersing a molded article of engineering plastic in a heated dye bath for several minutes followed by contact with cold water.

The molded articles that are colorized by the process are typically made from engineering plastics. Engineering plastics are polymers having high strength, stiffness, and toughness along with high thermal and oxidative stability, low creep, and the ability to be processed by standard techniques for thermoplastics. Exemplary engineering plastics are polyacetal, polyamide (nylon), polyurethane, polycarbonate, polysulfide, polysulfone, polyimide, polybutylene terephthalate, acrylonitrile butadiene styrene, polypropylene, polyvinyl chloride, polyethylene (high molecular weight and ultra high molecular weight), polyethylene terephthalate, polyester, and polytetrafluoroethylene resins. In various embodiments, the molded articles are skate blade holders, goalie skate cowlings, lacrosse racquet heads, and hockey or lacrosse helmets. In various preferred embodiments, the molded articles are skate blade holders made of nylon or polycarbonate.

In various embodiments, the dye bath used in the process of the invention is prepared in a vessel that is large enough for complete submersion of the molded article or the portion of the molded article to be dyed. The dye bath is prepared by placing an aqueous solvent, particularly water (in preferred embodiments, distilled water), in the vessel and heating the solvent to about 90° C.-100° C. Once the solvent reaches the desired temperature, the dye is added. Generally, the dye is added at about 1 ounce of dye for every 4 to 6 quarts of solvent or about 28 g of dye for every 4 to 6 liters of solvent. In various preferred embodiments, the dye is added at about 1 ounce of dye for every 5 quarts of solvent or about 28 g of dye for every 5 liters of solvent. The dye and solvent are thoroughly mixed and the temperature of the resulting dye bath is reduced. In various embodiments, the temperature of the dye bath is about 50° C. to about 100° C., preferably, about 60° C. to about 100° C., more preferably, about 70° C. to about 99° C., even more preferably, about 90° C. to about 99° C.

The dyes used in the dye bath can be those dyes known to a person skilled in the art. Particularly, commercial dyes including Rit® dyes can be used in the dye bath. Solid or liquid dyes can be used, but solid dyes are preferred. Such dyes can include surfactants and other additives in addition to dye compounds. Custom colors can be prepared by following variations of the color recipes provided for Rit® ProLine dyes and dependes on the material to be colorized.

Typically, the solvent used in the dye bath is an aqueous solvent. Thus, the main component of the solvent is water. Various other water miscible solvents can be added to the water. However, in preferred embodiments, the solvent is water. In some embodiments of the process, the solvent can be distilled water.

Optionally, the dye bath can include various additives such as NaCl, KCl, NaHCO₃, and vinegar (CH₃COOH). In various preferred embodiments, vinegar is added in an amount which increases the color uptake of the molded article when it is submersed in the dye bath. The amount of vinegar used ranges from about 0.25 tablespoon vinegar/quart water to about 0.5 tablespoon vinegar/quart water.

Generally, the first step of the process of imparting color to a molded article is preparation of the dye bath. The dye bath is prepared and the temperature of the dye bath is adjusted as described above. The molded article can then be submersed in the dye bath. Typically, the molded article is submersed from about 6 to about 10 minutes, preferably, from about 7 to about 8 minutes, but the time of submersion is not narrowly critical. In some embodiments, the molded article is submersed for about 1 to 1.5 hours. The time for submersion depends on the temperature and concentration of the dye bath, the depth of color desired for the molded article, and the type of engineering plastic. Thus, if keeping the other variables constant, a shorter time of submersion produces a molded article having a less intense color.

After removing the molded article from the dye bath, the molded article is immediately washed with cold water to cool the molded article and remove excess dye.

The following examples illustrate the invention.

EXAMPLE Example 1 General Process for Imparting Color to Skate Blade Holders

A metal vessel sufficiently large to allow complete submersion of the ice skate blade holder or goalie cowling was used, such as a 16 to 24 quart cooking pot. The vessel was filled with sufficient water to allow complete submersion of the ice skate blade holder or goalie cowling, normally to about 70-85% of capacity. The water was then brought to a slow boil at a temperature in the range of 97.8-101.1° C. (208-214° F.). Once the water reached this temperature, a commercially-available Rit® brand powdered dye is added to the water in the amount of one (1) ounce of dye for every five (5) quarts of water. In some of these experiments, vinegar was added to the solution at a concentration of about 0.25 tablespoon vinegar/quart water to about 0.5 tablespoon vinegar/quart water. The dry dye was then thoroughly mixed with the water to form a dye solution. The temperature of the dye solution was reduced to between 82.2° C. (180° F.) and 93.3° C. (200° F.). The holder was then submersed in the dye solution for seven (7) to eight (8) depending on the intensity of the color desired. A longer submersion time resulted in greater color intensity. The holder was then removed from the water and immediately rinsed with cold water.

Example 2 Variations of General Process

Time of submersion. When the skate blade holder was submersed for shorter than seven (7) minutes, generally the color produced was not as desirable because it was not deep or vibrant enough. When the skate blade holder was submersed for longer than eight (8) minutes, the quality of the color imparted was not appreciably affected for some dyes. For other dye colors, particularly darker dye colors, such as blue or black, a submersion time of 14 to 16 minutes was desirable. For some skate holder materials, such as translucent Lexan®, the submersion time was 1 to 2 hours.

Temperature of dye bath. Generally, the process was most effective when the temperature of the dye bath during submersion of the skate blade holder was between about 71.1° C. (160° F.) to about 98.8° C. (210° F.). It was found that dye bath temperatures higher than 93.3° C. (200° F.) do not impact the quality or time of coloration and temperatures lower than 82.2° C. (180° F.) begin to increase the processing time for imparting desirable color or reduce the depth of the color imparted to the skate blade holder. Preferably, the temperature of the dye bath is from about about 87.8° C. (190° F.) to about 93.3° C. (200° F.)

Type of dye. Three types of dyes were tested and Rit® brand dye produced skate blade holders having the most desirable appearance, though the other dyes did impart color to the skate blade holders. Rit® brand liquid dye products were also tested, but the skate blade holders using the liquid dye did not produce acceptable results. In some cases, the color resulting was acceptable, but the costs for the same product was much greater than use of solid dyes. A number of standard Rit® brand dye colors and a few custom blends of dyes were tested. Skate blade holders having a desirable appearance were produced in the following colors: red, royal, black, yellow, gold, purple, pink, navy, Columbia blue, sunshine orange, and lime.

Additives to the dye bath. Small amounts of common household chemicals such as NaCl, KCl, vinegar (CH₃COOH), and NaHCO₃ were also added to the dye bath for some experiments. Although NaCl, KCl, and NaHCO₃ did not produce a considerable difference in the results of the process, in some cases they did produce very slight differences in the depth of color and shades of color imparted to the skate blade holders. Therefore, these additives can be used to achieve a desired color depth or shade. When vinegar was added the color uptake to the skate holder was enhanced. A small amount (e.g., 0.25 tablespoon vinegar/quart water to about 0.5 tablespoon vinegar/quart water) was used for this purpose.

Deionized water. Use of deionized (or distilled) water as the solvent in the dye bath produced skate blade holders with slightly shinier finishes. However, the added cost of this solvent outweighed the incrementally improved appearance of the skate blade holder.

When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above compositions and processes without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. 

1. A process for imparting color to a molded article comprising submersing at least a portion of the molded article in a dye bath comprising an aqueous solvent and a dye wherein the molded article is comprised of an engineering plastic.
 2. The process of claim 1 wherein the aqueous solvent is water.
 3. The process of claim 1 wherein the dye is a commercial dye.
 4. The process of claim 1 wherein the dye bath is at a temperature from about 50° C. to about 100° C.
 5. The process of claim 4 wherein the dye bath is at a temperature from about 80° C. to about 100° C.
 6. The process of claim 4 wherein the dye bath is at a temperature from about 90° C. to about 99° C.
 7. The process of claim 5, wherein about 28 g dye is mixed with about 4 to about 6 liters water to form the dye bath.
 8. The process of claim 7, wherein about 28 g dye is mixed with about 5 liters water to form the dye bath.
 9. The process of claim 7 wherein the molded article is submersed in the dye bath for about 3 to about 8 minutes.
 10. The process of claim 5 wherein the molded article is submersed in the dye bath for about 7 to about 8 minutes.
 11. The process of claim 1 wherein the molded article is an ice skate blade holder.
 12. The process of claim 1 wherein the molded article is a goalie skate cowling.
 13. The process of claim 1 wherein the molded article is a hockey helmet, lacrosse helmet, or a lacrosse racquet head.
 14. The process of claim 1 wherein the molded article comprises polyacetal, polyamide (nylon), polyurethane, polycarbonate, polysulfide, polysulfone, polyimide, polybutylene terephthalate, acrylonitrile butadiene styrene, polypropylene, polyvinyl chloride, high molecular weight polyethylene, ultra high molecular weight polyethylene, polyethylene terephthalate, polyester, or polytetrafluoroethylene resins.
 15. The process of claim 1 wherein the molded article is made of polyamide (nylon) or polycarbonate.
 16. The process of claim 15 wherein the molded article is a skate blade holder or goalie skate cowling.
 17. The process of claim 16 wherein the dye bath further comprises vinegar.
 18. The process of claim 17 wherein the dye bath comprises 0.25 tablespoon vinegar/quart water to about 0.5 tablespoon vinegar/quart water.
 19. The process of claim 7 wherein the molded article comprises polyacetal, polyamide (nylon), polyurethane, polycarbonate, polysulfide, polysulfone, polyimide, polybutylene terephthalate, acrylonitrile butadiene styrene, polypropylene, polyvinyl chloride, high molecular weight polyethylene, ultra high molecular weight polyethylene, polyethylene terephthalate, polyester, or polytetrafluoroethylene resins.
 20. The process of claim 7 wherein the molded article is made of polyamide (nylon) or polycarbonate. 